topic Re: Nested Fault Domains for 2-node STRECHED clusters in VMware vSAN Discussions

Nested Fault Domains for 2-node STRECHED clusters

vmb01 — Wed, 01 Jun 2022 14:37:30 GMT

If I deploy a streched cluster composed by 2 nodes (in the config guide I select streched NOT 2 hosts),

The "Nested Fault Domains for 2-node clusters" is available ?

Re: Nested Fault Domains for 2-node STRECHED clusters

TheBobkin — Wed, 01 Jun 2022 18:17:02 GMT

@vmb01, interesting question - I am not aware of any pertinent variance in the backend settings applied to node for each cluster type that would cause any difference here.

If you have this already configured as stretched, you should be able to easily check this by creating the policy that would store data like this and validate whether it shows the vsanDatastore for this cluster as compatible (and if it does then validate by creating a test VM with this policy):

Re: Nested Fault Domains for 2-node STRECHED clusters

pkvmw — Thu, 02 Jun 2022 08:04:53 GMT

Nested Fault Domains are available for 2-node clusters, yes. But it requires at least 3 disk groups per host to have in-host RAID1:
https://core.vmware.com/blog/nested-fault-domain-2-node-cluster-deployments

Also interesting read: https://www.yellow-bricks.com/2022/03/17/stretched-cluster-witness-failure-resilience-in-vsan-7-0/

Re: Nested Fault Domains for 2-node STRECHED clusters

depping — Thu, 02 Jun 2022 08:22:11 GMT

I have never seen a support statement around it to be honest,

Re: Nested Fault Domains for 2-node STRECHED clusters

AndreaScarabell — Fri, 03 Jun 2022 10:11:21 GMT

Indeed we would not be able to find any docs about it.

You know, if the nested fault domain would be available also for 1+1+1 streteched cluster, we'll be able to compete with Symplivity and Datacore (I mean: from a data resiliency point of view)

Re: Nested Fault Domains for 2-node STRECHED clusters

depping — Fri, 03 Jun 2022 11:36:51 GMT

I don't see why it wouldn't be supported, even 2 node stretched is still 2 node, I would assume it is okay, but let me drop a note to a product manager and ask.

Re: Nested Fault Domains for 2-node STRECHED clusters

vmb01 — Mon, 13 Jun 2022 10:37:56 GMT

Hi Duncan, do you have any news, from the PM, about it ?

Re: Nested Fault Domains for 2-node STRECHED clusters

depping — Tue, 14 Jun 2022 09:28:31 GMT

No news, just reminded him.

Re: Nested Fault Domains for 2-node STRECHED clusters

depping — Mon, 20 Jun 2022 10:03:54 GMT

I just heard that we do support it in a two node configuration which happens to be stretched. Do note, you will need 3 diskgroups at a minimum per host to support it.